[HECnet] Recommendation on replacement Dallas DS1287A

Gurus, I'm looking for your advice. My DEC 3000 gave me a POST NVR error and after trying all the steps to fix it (reseating boards, memory, etc...) it looks like the RTC (DALLAS DS12871A) has died. Searching on line I found some places marketing a replacement for DS1287 for old PC's but not sure if any would work for DEC given it had an A at the end in the model number (different pins etc...) Given that this sounds like a common problem on early VAXen, I was wondering if of you have some recommendations on a good source to purchase a replacement RTC that will work with DEC equipment. Thanks much! Mike